Coffee oftentimes comes with milk foam. Conventional milk foaming devices may be individually set up, or be integrated into automated coffee machines. At present, for cleaning purposes, the aforementioned milk foaming devices have to be dissembled beforehand, which is rather inconvenient, usually leading to periodic cleaning at relatively long time intervals. However, milk accumulated therein for such a long period is easily spoiled and generates a lot of germs, thereby raising hygienic concerns.